Portable environmentally robust enclosure optimized for size, weight, and power dissipation

ABSTRACT

An enclosed electronic apparatus including a first continuous heat-transfer band forming at least a portion of the exterior surface of the enclosure, with continuous lateral edges on either side thereof, and mounting points on an internal side of the continuous heat transfer band to which a printed circuit board assembly is mountable. A printed circuit board assembly is mounted to the heat transfer band at the mounting points, with a thermally conductive portion forming a thermal path between a heat-producing electronic component of the printed circuit board assembly and the heat transfer band. A thermally conductive gasket between the printed circuit board assembly and the heat transfer band at the mounting points facilitates heat transfer. Opposing first and second enclosure portions seal the respective continuous lateral edges of the heat transfer band against penetration of fluid or debris. It is small, compact, lightweight, rugged and otherwise ergonomic for ease of use and protection from accidental impact caused by, for example, dropping the unit. The reliability of the system is improved because the internal electronic components are protected from moisture, dust, and other liquid or particle contaminants, all while maintaining an internal temperature that is lower than a maximum permissible operating temperature.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit and priority of U.S. Non-Provisionalpatent application Ser. No. 12/194,652 filed Aug. 20, 2008 entitledPORTABLE ENVIRONMENTALLY ROBUST ENCLOSURE OPTIMIZED FOR SIZE, WEIGHT,AND POWER DISSIPATION, the entire disclosure of which is incorporatedherein by reference.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to the field of electronics packaging, andmore particularly to a robust enclosure having reduced size and weightand increased power dissipation capacity.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an enclosedelectronic apparatus including a first continuous heat-transfer bandforming at least a portion of the exterior surface of the enclosure,with continuous lateral edges on either side thereof, and mountingpoints on an internal side of the continuous heat transfer band to whicha printed circuit board assembly is mountable. A printed circuit boardassembly is mounted to the heat transfer band at the mounting points,with a thermally conductive portion forming a thermal path between aheat-producing electronic component of the printed circuit boardassembly and the heat transfer band. An optional thermally conductivegasket between the printed circuit board assembly and the heat transferband at the mounting points facilitates heat transfer. Opposing firstand second enclosure portions seal the respective continuous lateraledges of the heat transfer band against penetration of fluid or debris.

The enclosed electronic apparatus may include more than one continuousheat-transfer bands, while maintaining the sealed integrity of theenclosure. The plural continuous heat transfer bands may be sequentiallylocated adjacent each other, including a thermally conductive gasketbetween them, or they may have additional enclosure section interposedbetween them, again with optional continuous gaskets for sealing.

The enclosed electronic apparatus may include one or more printedcircuit board assemblies, either mounted in a generally continuous planeor mounted in respective offset planes. A fan may be provided tocirculate coolant fluid, e.g., air, over the surface of the at one ormore printed circuit board assemblies.

The enclosure may optionally includes one or more of an integralgraphical user interface, a user keypad, an encoder knob, and sealedaccess doors for communication ports and/or an internal battery. Thegraphical user interface would be viewable through a sealed transparentwindow in the enclosure, and may itself be in thermal communication withthe continuous heat transfer band to dissipate heat generated by itsoperation within the enclosure. Access doors, such as for battery accessor communication access are preferably sealed by continuous gaskets, andselectively securely held in their closed position to maintain theintegrity of the enclosure.

In the case where an encoder knob is provided, an encoder shaft openingin the enclosure admits the shaft of an encoder mounted with theelectronic apparatus. A continuous shaft gasket in compression betweenthe encoder shaft and the encoder shaft opening. The encoder knob ismounted to the encoder shaft, and preferably covers the area of encodershaft opening. A sealing grease may be applied to the interface betweenthe encoder shaft opening and the continuous shaft gasket, and to theinterface between the continuous shaft gasket and the encoder shaft.Preferably, the encoder knob presents a small clearance between itselfand the surface of the respective enclosure, and/or a small clearancebetween itself and a wall of the encoder shaft opening, both to inhibitpenetration of external fluid or debris.

According to the present disclosure, a plurality of shock resistingbumpers may be secured to an exterior of the electronic apparatus, suchthat a linear surface between any two adjacent shock resisting bumperswould contact only the bumpers, and not any other part of the apparatus.Where the apparatus is generally the shape of a rectangularparallelepiped, the plurality of shock resisting bumpers are preferablypositioned to cover at least the eight corners of the rectangularparallelepiped. Shock resisting bumpers may also protect a protrusion ofa compartment extending from the enclosure.

The printed circuit board assembly may optionally, include a heatconducting covering in thermal contact with an exposed surface of a heatgenerating component of the PCB assembly, and connected to thecontinuous heat transfer band, forming a further thermal path betweenthe heat generating component and the continuous heat transfer band. Athermal gasket and/or a thermal grease interposed between the heatconductive covering and the heat generating component may aidconduction.

A thermally conductive portion of the printed circuit board assembly mayalso include a thermally conductive internal layer within the surface ofthe printed circuit board. One or more thermally conductive regions on aperimeter of the printed circuit board assembly are in thermalcommunication with the thermally conductive portion between theheat-producing electronic component of the printed circuit boardassembly and the heat transfer band. Further, thermally conductiveinterior regions of the printed circuit board assembly may also be inthermal communication with the thermally conductive portion between theheat-producing electronic component of the printed circuit boardassembly and the heat transfer band.

A plurality of thermally conductive regions and/or heat generatingcomponents may be located on opposing sides of the printed circuit boardassembly.

BRIEF DESCRIPTION OF THE DRAWING(S)

These and other features, benefits and advantages of the presentdisclosure will be made apparent with reference to the followingdetailed description, including the appended claims, and theaccompanying figures, wherein like reference numerals refer to likestructures across the several views, and wherein

FIG. 1 illustrates a front view of the instrument enclosure of anexemplary embodiment of the present disclosure;

FIG. 2 illustrates an enclosure interior rear view of the heat transferband assembly of the exemplary embodiment;

FIG. 3 illustrates a detailed right side cross-sectional view of theenclosure assembly of the exemplary embodiment;

FIG. 3 a illustrates a simplified left side view of enclosure assemblyof the exemplary embodiment;

FIG. 3 b illustrates in greater detail the portion of the PCB systemmounting hardware circumscribed by 3B in FIG. 3 a;

FIG. 4 illustrates an enclosure interior front view of the heat transferband and LCD mounting plate assembly of the exemplary embodiment;

FIG. 5 illustrates an encoder shaft sealing system of the exemplaryembodiment;

FIG. 5 a illustrates in greater detail the portion of the an encodershaft sealing system circumscribed by 5A in FIG. 5;

FIG. 6 illustrates an alternate embodiment of the heat transfer bandwith a plurality of mounted PCB assemblies;

FIG. 7 illustrates an alternate embodiment using a plurality of heattransfer bands;

FIG. 7 a illustrates an further alternate embodiment using a pluralityof heat transfer bands;

FIG. 8 illustrates an exemplary PCB assembly heat transfer system;

FIG. 8 a illustrates a cross sectional view of exemplary PCB assemblyheat transfer system;

FIG. 9 illustrates an enclosure side view with IO access door;

FIG. 10 illustrates an enclosure front view with planar impact surfaces;

FIG. 11 illustrates an enclosure side view with planar impact surfaces;and

FIG. 12 illustrates a simplified left side view of enclosure assembly ofalternate embodiment with exemplary PCB heat transfer covering.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Certain electronic components, including NDI (Non-DestructiveInspection) devices, using e.g., ultrasonic, eddy currents, or the like,such as are contemplated for use with the enclosure herein disclosed,are used in a wide variety of harsh industrial environments andconditions. Environments associated with the inspection of pipelines,for example, range from arctic to desert conditions and all forms ofwhether in between. Nautical environments are also encountered wherethere is not only excessive moisture, but also salt water, which can becorrosive.

The instrument enclosure of the present disclosure ameliorates theunfavorable effects of said environments because it is optimized toperform without failure under a wide range of environmental andoperating conditions. Furthermore, it is preferably small, compact,lightweight, rugged and otherwise ergonomic for ease of use andprotection from accidental impact caused by, for example, dropping theunit.

The reliability of the instrument is improved because the internalelectronic components are protected from moisture, dust, and otherliquid or particle contaminants, all while maintaining an internaltemperature that is lower than a maximum permissible operatingtemperature.

Specifically, the enclosure is preferably entirely sealed and includes ameans to transfer the internally dissipated heat to the externalenvironment, while maintaining robustness and ergonomics—i.e. smallsize, low weight, and well placed center of mass.

In addition, a variety and/or plurality of heat transfer bands can beused with a common set of enclosure parts. This provides the means toquickly respond to customer needs and economically produceapplication-specific instruments that use different heat transfer bandsdepending on the need for optimization. Examples of instrumentcharacteristics that can be optimized by this method are heat transfer,weight, size, cleaning method and the number of circuit boards used.

More specifically, heat transfer can be optimized by increasing theexternal and/or internal surface area of the heat transfer band, such asby the means of heat transfer fins. Heat transfer may also be optimizedby material selection and processing. Weight can be reduced byminimizing the volume and/or changing the type of material used for theheat transfer band. Enclosure size can be reduced by making the heattransfer band narrower, as could be the case when using one, instead oftwo parallel, PCB assemblies; or using PCB assemblies with lower heightprofiles. Size can also be reduced by minimizing or removing theexternal heat transfer fins, within the constrains of the power to bedissipated. Finally, enclosure size can be increased to adapt to aplurality of PCB's that need to have their heat transferred by means ofthe heat transfer band described herein. This can be done by couplingindividual heat transfer bands together with other enclosure parts. Toaccommodate more than two PCB assemblies per heat transfer band, PCBmounting ledges at different elevations may by used (see, FIG. 6).

Furthermore, a system of external bumpers is used to mitigate theaffects of shock and vibration that are typically associated withaccidental dropping and transportation over long distances,respectively. The primary concerns associated with dropping, orotherwise shocking a unit, include induced PCB board flexure, whichapplies strain to the soldered connections between component mountingpins, or balls, and PCB pads. Very fine traces and internal PCBconnections, such as vias, will also be strained. When the strain isexcessive, the connections are damaged and become unreliable. A shockimpulse can cause larger mass components, such as inductors andbatteries, to become dislodged or otherwise compromised. Typically,shock resistance of electronic assemblies is achieved by use of strongimpact resistant enclosure materials and a non-rigid mounting method forPCB assemblies—using rubber mounting grommets, for example. In somecases, shock absorbing materials, such as rubber, are applied to theexterior of the enclosure.

The strong impact resistant material prevents the enclosure fromcracking, and in some cases absorbs shock when the material has theability to deflect without causing damage. The non-rigid mounting methodfor PCB assemblies prevents torsional forces caused by enclosuredeformation during impact from being substantially transferred to thePCB board, thereby minimizing flexure and the attendant problemsdescribed previously.

The preferred embodiment of the present disclosure combines a metallicheat transfer band with light weight and durable plastic front, rear,and other enclosure parts. The thermal management system of thepreferred embodiment is therefore at odds with the conventional shockresistant design described above in the following ways. PCB assembliesmust be rigidly mounted to the heat transfer band to maximize theconduction of heat that must flow to the exterior of the enclosure in anefficient a manner. Furthermore, rubber bumpers used on the exterior ofthe enclosure must be kept to a minimal size in order to maximize theexposed surface area of the heat transfer band for optimal heatconvection with the surrounding air. The system of external bumpers ofthe preferred embodiment addresses this problem by being located on theinstrument corner and outwardly protruding surfaces. These surfacesproviding the only surfaces that come into contact with the planarsurface that the instrument is dropped on, or otherwise applied to. As aresult, the exposed external surface of the heat transfer band ismaximized (for optimal heat convection), and the torsional and impulseforce on the heat transfer band and the rigidly mounted PCB assembliesis minimized (for shock protection).

In combination with the system of external bumpers, the enclosure hasits external connectors, knobs, fasteners, and other appendagespositioned in such a way as to prevent them from taking a direct hitwhen the instrument is dropped on a planer surface. In some cases, thisis true even when the connector of the mating cable assembly isconnected.

An alternate embodiment of the present disclosure is contemplated thatdoes not include a display, keypad or battery, but rather is just asealed enclosure with the heat transfer band sandwiched between a frontand rear enclosure section in a similar fashion as the preferredembodiment. The mounting of a plurality of heat transfer bands and theuse of different heat transfer bands as described for the preferredembodiment is also contemplated for this alternate embodiment.

Referring now to FIG. 1, illustrated is a front view of the instrumentenclosure, generally 100, of a first embodiment of the presentdisclosure. Visible from the front of the enclosure 100 are an LCDwindow 101. The enclosure includes shock resisting bumpers 102 a through102 f, positioned to guard each of the eight corners of the enclosure100, which in this embodiment is generally in the shape of a rectangularparallelepiped, in a manner that will be described further, below. Anexterior of the enclosure 100 includes plate mounted transducerconnectors 103, which in the exemplary embodiment may interface with atransducer of a Non-Destructive Inspection probe (not shown). A heattransfer band 104 extends around at least one, and preferably four,lateral sides of the enclosure 100. The enclosure 100 further includesan I/O port access door 105 permitting access to wired communicationports in the enclosure 100. A bottom adjustable support stand 106 inconnected to the enclosure 100 on pivot mounts 106 a. The enclosure alsomay include a rubberized carrying handle 107.

Referring now to FIG. 2, illustrated is an enclosure interior rear viewof the heat transfer band assembly, generally 200, according to thisexemplary embodiment of the present disclosure. The heat transfer bandassembly 200 as viewed form the rear includes plate mounted transducerconnectors 103 (also visible in FIG. 1), and also shows plate mountedconnector transducer cable assemblies 103 a and 103 b, and PCB (printedcircuit board) mating connectors 103 c and 103 d for transducer cableassemblies 103 a and 103 b, respectively. Heat transfer band 104includes a perimeter ridge 104 a. I/O access door 105 (also visible inFIG. 1) can also be seen. Compression blocks 201 include compressionblock fasteners and mating holes 201 a, and compression block tappedholes 201 b.

Also visible in the interior rear view of FIG. 2 is the rear PCBassembly 203. Heat transfer band 104 is mounted to the rear PCB assembly203 by one or more heat transfer band mounting screws 204. A fan 205circulates coolant, typically as in this case air, throughout theinterior of the enclosure 100 including over the rear PCB assembly 203.

FIG. 3 illustrates a detailed right side view of enclosure 100 accordingto the present embodiment. FIG. 3 shows the shock resisting cornerbumpers 102 a, d and e. Heat transfer band 104 is visible near the topand bottom extremities of the enclosure 100. The bottom adjustablesupport stand 106 is shown (also visible in FIG. 1). The rear PCBassembly 203 of FIG. 2 is also visible, as is a portion of fan 205. Afront PCB assembly 301 is shown, having a PA interface PCB assembly 303.LCD 305 faces a front enclosure 307 of the enclosure 100. Acomplementary rear enclosure 308, together with front enclosure 307,border either side of the heat transfer band 104. A battery door 309 onthe rear enclosure permits access to the batter 310. Battery door 309 issecured by battery door fastener screws 309 a through d. The batterydoor also has its own shock resisting battery door bumpers 311 a throughd.

Referring now to FIG. 4, illustrated is an enclosure interior front viewof the heat transfer band and LCD mounting plate assembly of the presentembodiment. Heat transfer band assembly 400 includes heat transfer band104. Fan 205 circulates coolant, typically as in this case air, over thePBC assemblies within the enclosure 100. A front PCB assembly 301includes LCD 305, which is carried on LCD mounting plate 403. The LCDmounting plate 403 is secured by LCD mounting plate fasteners 403 a.

Referring now to FIG. 5, illustrated is an encoder shaft sealing system,generally 500, according to the present embodiment. It should be notedthat the inclusion of encoder 501 or its associated sealing system 500is not required for all embodiments of the instrument of the presentdisclosure.

Shaft 501 a of encoder 501 is surrounded by edge 502 b of continuousgasket 502. Exterior edge 502 a of gasket 502 abuts the wall surface offront enclosure 307. Preferably, edge 502 a is held under compression bythe mating wall surface of front enclosure 307. O-ring grease (notshown) is optionally applied to any abutting surfaces to substantiallyeliminate air gaps in the sealing regions.

According to the present embodiment the sealed surfaces are comprised ofthe following abutment relationships: shaft 501 a to continuous gasket502 to wall surface of front enclosure 307. Accordingly, the encodershaft sealing method prevents moisture and particles from entering theinterior region of enclosure 100.

Furthermore, the geometry of encoder knob 108 and its relationship tothe surfaces of front enclosure 307 is optimized to diffuse liquidssprayed under high pressure before they enter region 506 wherecontinuous gasket 502 is located. Said diffusion minimizes the force andamount of liquid entering region 506. Surface 108 a of encoder knob 108is located only a short distance away from the front surface of frontenclosure 307, and surface 108 b is located only a short distance awayfrom the wall surface of front enclosure 307 that encircles it. Saiddistances are as short as can be achieved within the combined tolerancesof the said parts and assembly method.

The amount of sprayed water entering region 506 is restricted by saiddistances; therefore, it is advantageous for these distances to be asshort as possible without interfering with any other aspects offunctionality, such as restricting the ease of rotation of encoder shaft501 a.

Referring now to FIG. 6, illustrated is an alternate embodiment of theheat transfer band with a plurality of mounted PCB assemblies. A heattransfer band assembly, generally 600 is comprised of heat transfer band602. Plural PCB assemblies are mounted to the heat transfer band 602,and include an outer rear PCB assembly 604, an inner rear PCB assembly605, and inner front PCB assembly 606, and an outer front PCB assembly607. Similar to the prior embodiment, also included is an LCD 609, whichis viewable through an LCD window 609 a in the front enclosure 603. AnLCD thermal gasket 609 b facilitates heat flow from the LCD 609 to theheat transfer band 602 through the LCD mounting flange 608.

The front enclosure 603 is secured to the heat transfer band 602 viamounting bosses 603 a, 603 b. Similarly, rear enclosure 601 is securedto the heat transfer band 602 via mounting bosses 601 a, 601 b. Gaskets610 and 611 seal the rear enclosure 601 and the front enclosure 603,respectively, against the heat transfer band 602 at its respectivelateral edges. Like the heat transfer band 602, and particularly itsfront and rear edges, the gaskets 610, 611 are continuous to effectivelyseal the enclosure 600 against ingress of water or contaminants at theinterface of the heat transfer band 602 with front enclosure 603 andrear enclosure 601. Either or both of the gaskets 610, 611 may be athermally conductive gasket to aid thermal dissipation by facilitatingheat flow to the heat transfer band 602.

The embodiment of FIG. 6 may be further modified to include fewer ormore PCB assemblies, including an odd number of PCB assemblies.

Referring now to FIG. 7, illustrated a further alternate embodimentusing a plurality of heat transfer bands. Heat transfer band assembly,generally 700, according to this embodiment is comprised of plural heattransfer bands 703, 705. Plural PCB assemblies are mounted to the heattransfer bands 703, 705, and include and outer rear PCB assembly 711,and inner rear PCB assembly 712, and inner front PCB assembly 713, andan outer front PCB assembly 714. Additionally, LCD 709 is displayedthrough and LCD window 708 in the front enclosure 707. An LCD thermalgasket 709 b facilitates heat flow from the LCD 709 to the heat transferband 705 through the LCD mounting flange 710.

The front enclosure 707 is secured to the heat transfer band 705 viamounting bosses 707 a, 707 b. Similarly, rear enclosure 701 is securedto the heat transfer band 703 via mounting bosses 701 a, 701 b. Gaskets702, 704, and 706 seal the rear enclosure 701 against heat transfer band703, heat transfer band 703 against heat transfer band 705, and thefront enclosure 707 against heat transfer band 705, respectively at therespective lateral edges of front and rear enclosures 701, 707 and heattransfer bands 703, 705. Like the heat transfer bands 703, 705, andparticularly their respective lateral edges, the gaskets 702, 704 and706 are continuous to effectively seal the enclosure 700 against ingressof water or contaminants at the interface of the heat transfer bands703, 705 with front enclosure 707 and rear enclosure 701. One or more ofthe gaskets 702, 704 and 706, in particular gasket 704 between heattransfer bands 703 and 705, may be a thermally conductive gasket, whichwould facilitate distribution of any thermal imbalance between the heattransfer bands 703, 705, and aid thermal dissipation by taking advantageof the combined external surface area of the heat transfer bands 703,705.

Referring now to FIG. 7 a, illustrated is a further alternate embodimentusing a plurality of heat transfer bands. As depicted in FIG. 7 a,enclosure wall segment 716 with associated mounting bosses 716 a, 716 b,may be used to couple heat transfer bands 703 and 705 together by meansof fasteners as described earlier. A gasket 717 and enclosure section716 are interposed between gasket 704 and heat transfer band 705.

It should be noted that the structure and methods of these embodimentsare not limited to two heat transfer bands. Accordingly, a plurality ofheat transfer bands may be used. Moreover, with reference to FIGS. 3 a,7, any heat transfer band 104, 602, or 702 & 705, respectively, may beassembled to the same mating parts. Specifically, either front enclosuresections (e.g., 307) or rear enclosure section (e.g., 308) and theirassociated gaskets and fastener hardware. Accordingly, the electronicsystem utilizing the enclosure of the present disclosure may be mademodular, so that certain PCB assemblies, or combinations thereof, may beprefabricated to respective heat transfer rings (e.g., 104), and thesemay be substituted and/or stacked.

Similarly, the mating enclosure parts (e.g., front enclosure 307 or rearenclosure 308) may be those of the preferred embodiment of the presentdisclosure, or may be substituted with other parts, such as those usedto simply house the internal electronics and provide interconnectwiring, and/or mounting provisions, but without some or all of anintegral graphical user interface (e.g., LCD 305), keypad (shownintegrated with front surface 101 a; FIG. 1), or encoder knob 108.

Referring now to FIG. 8, illustrated is an exemplary PCB assembly heattransfer system, generally 800, according to the present disclosure. ThePCB assembly heat transfer system 800 is comprised of mounting holes801, useful for securing the PCB assembly heat transfer system 800 to aheat transfer ring, e.g. 104 as described, above. Perimeter heatconduction vias 802 conduct heat from associated perimeter heatconduction regions 803. Interior heat conduction vias 804 conduct heatfrom associated interior heat conduction regions 806. Heat conductionvias 804 a are located beneath associated electronic components 805 athrough 805 d. Heat conduction vias 803, 804, and 804 a each connecttheir respecting heat conduction regions with a thermally conductiveinternal layer 807 generally throughout the PCB assembly heat transfersystem 800. FIG. 8 a illustrates a vertical cross-section of the PCBassembly heat transfer system 800, including the respective locations ofperimeter heat conduction regions 803, interior heat conduction regions806, vias 802, 804, and thermally conductive internal layer 807.Cross-sectional view of FIG. 8 a shows vias 802, 804 extending from bothsurfaces of the PCB assembly heat transfer system 800, with surface heatconduction regions on both sides thereof. The PCB assembly heat transfersystem 800 may be populated with electronic components, e.g., 805 athrough 805 d, on both sides, or may have such components on only oneside thereof.

Referring now to FIG. 10, illustrated is an enclosure front view withplanar impact surfaces. In particular, illustrated is the manner inwhich shock resisting bumpers 102 a through 102 f absorb any planarimpact spanning any two adjacent bumpers. Left side bumpers 102 a and102 d come into contact with planar surface 1001 thereby preventing theleft side of heat transfer band 104 from doing so. The same holds truerespectively for right side bumpers 102 b and 102 c with respect toplanar surface 1004 and the right side of heat transfer band 104; bottombumpers 102 d and 102 c with respect to planar surface 1005 and thebottom side of heat transfer band 104; top bumpers 102 a and 102 e withrespect to planar surface 1002 and plate mounted transducer connectors103; top bumpers 102 e and 102 f with respect to a parallel planarsurface (not shown) above it and the top right side of heat transferband 104; and top bumpers 102 f and 102 b with respect to planar surface1003 and the top right-most side of heat transfer band 104. These planarsurfaces ignore the possible interference of rubberized carrying handle107, which itself may absorb some or all of an impact before the planarimpact surface reaches one or more of shock resisting bumpers 102 athrough 102 f.

Referring now to FIG. 11, illustrated is an enclosure side view withplanar impact surfaces. As illustrated in FIG. 11, bumpers 102 a and 102d, or 102 b and 102 c (not shown) come into contact with planar surface1101 thereby preventing the front surface of the enclosure from doingso. The same holds true respectively for bumpers 102 a, 102 b, 102 e,and 102 f (102 e and 102 f not shown in FIG. 11) with respect to planarsurface 1102 and an upper portion of front enclosure 307 and heattransfer band 104; bumpers 102 a, 102 b, 102 e, and 102 f (102 e and 102f not shown in FIG. 11) with respect to planar surface 1103 and an upperportion of rear enclosure 308 and heat transfer band 104; bumpers 102 a,and 102 b, and battery door bumpers 311 a, 311 b, 311 c and 311 d (311 band 311 c not shown in FIG. 11) with respect to planar surface 1104 andthe upper portion of rear enclosure 308, including connectors 901 a, 901b and 901 c, which may alternatively any protruding object attached tothe enclosure; and battery door bumpers 311 a, 311 b, 311 c and 311 d(102 b, 311 b and 311 c not shown in FIG. 11) with respect to planarsurface 1105 and battery door 309.

Referring now to FIG. 12, illustrated is a simplified left side view ofenclosure assembly of alternate embodiment with exemplary PCB heattransfer covering. In this embodiment PCB assembly 203 e has heatconducting elements 203 a and b that are coupled to heat transfer band104 in at least one, but preferably two locations.

Exemplary heat conduction elements 203 a and b are composed of anefficient heat conducting material, such as aluminum or sheet metal,having a topographical profile suitable for compression contact with topsurfaces of heat generating components 203 c and 203 d, and coupling toheat transfer band 104. Typically, a thermal gasket or grease (neithershown) is applied between the abutting surfaces of said heat conductionelements 203 a, 203 b, and heat generating components 203 c, 203 d, andheat transfer band 104 in order maximize heat conduction.

Heat conduction elements 203 a and b may be fabricated by a number ofmethods, with machining, die casting, and stamping being the mostprevalent. Furthermore, although not shown, said exemplary heatconduction elements 203 a, 203 b may be applied to any or all PCBassemblies that are coupled to a heat transfer band 104. When composedof a suitable material and geometry, heat conduction elements 203 a and203 b also serve as shields for electromagnetic signals that the PCBassemblies may radiate, or that they be susceptible to from externalsources.

The manner of operation of the foregoing components will now bedescribed in further detail.

The present disclosure is concerned with designing an instrument that isrugged, small, light weight and otherwise ergonomic while being capableof performing without failure under a wide range of environmental andoperating conditions. Instrument enclosure 100 is completely sealed toprevent moisture, liquid or dust from entering it.

The enclosure 100 of the present embodiment of the disclosure isintended to operate in environmental conditions that include a wideambient temperature range, preferably at least from −10 to 50 degCelsius. The present disclosure also provides a means to meet CE safetyspecification EN61010-1, which requires that any external enclosuresurface that can be touched not exceed 70 degrees Celsius when in 40degree Celsius external ambient air. The enclosure 100 must withstandvery wet environments, such as use in heavy rain or on vessels at sea.The enclosure must tolerate very dusty and dirty environments. Finally,the enclosure must withstand areas where it is likely that theinstrument will be accidentally dropped, or otherwise mechanicallyshocked.

An aspect of the preferred embodiment enclosure 100 is that it is usablefor a high performance NDI device, with a nominal power consumption of17 watts. The challenge is to dissipate this considerable power incompletely sealed enclosure 100, i.e. one in which there is no exchangeof internal and external air.

The heat transfer band 104 simultaneously serves as the principal meansof heat transfer from the interior to exterior of the enclosure (e.g.,FIGS. 2 and 9), a mount for PCB assembles (e.g., FIGS. 2, 3 and 3 a),and a structural part of enclosure forming a continuous band thatprovides a portion of the interior and exterior walls of the enclosure,and a continuous perimeter wall edges for abutment to gaskets locatedbetween the coupled surfaces of mating parts, i.e. the front and rearplastic housing parts. (e.g., FIGS. 2, 3 a and 9). The geometry of heattransfer band assembly 200 is optimized to minimize the volume it takesup in the enclosure, while still providing maximum PCB board space andample heat transfer.

With reference to FIGS. 2, 3 a, heat transfer band 104 encompasses theentire edge perimeter of the PCB's mounted within it (e.g., 203 and301), the elevation of components mounted on said PCB's not exceedingthe elevation of pre-established planar regions that run parallel to thePCB's top and bottom surfaces. Said regions, known as ‘keep out areas’,represent regions where no other parts of the enclosure may locate,typically to prevent mechanical interferences.

Enclosure Sealing System

With reference to FIGS. 1, 3 a and 9, there are four primary sectionsthat form the exterior and interior walls of enclosure 900, the edges ofwhich are coupled together with continuous gaskets 610 and 611 (FIG. 3a) or adhesive in between. It should be noted that the gaskets must bekept under compression by abutting surfaces of rear enclosure 308,gasket 610, heat transfer band 104, gasket 611 and front enclosure 307in order to provide desired sealing.

The abutment relationships forming the seals are: front enclosure 307 tocontinuous gasket 611 to heat transfer band 104; heat transfer band 104to continuous gasket 610 to rear enclosure 308; and rear enclosure 308to continuous gasket (not shown) to battery door 309.

The principal portions of enclosure 100 are fastened together by screws,the threaded portions of which are inserted through the mounting holesof front enclosure bosses 307 a & b and rear enclosure bosses 308 a & b,then into the holes provided for them in the respective sides of heattransfer band 104 (FIG. 3 a). This fastening method provides a means tokeep the gaskets in proper compression, thereby forming a continuousseal around the seams of said coupled parts.

Other sealed surfaces of the enclosure 100 are comprised of similarabutment relationships. Plate mounted transducer connectors 103 (FIG. 1)are sealed by a continuous gasket (not shown) to heat transfer band 104.Similarly, a plurality of panel mount or plate mounted connectors can besealed likewise by continuous gasket to a mating surface of theenclosure. The LCD window 101 (FIG. 1) may be sealed by and adhesive tothe front enclosure 307. Shaft 501 a (FIG. 5) of encoder 501 inconnection with encoder knob 108 is sealed by a continuous gasket 502 tothe front enclosure 307.

Continuing with FIG. 9, TO access door 105 protects data connectors, inthis embodiment four including USB and d-sub connectors, in region 903from moisture and dust when closed and securely fastened by means offasteners 105 c inserted into holes 902. Gasket 901 is kept under propercompression when TO access door 105 is securely fastened by fasteners105 c.

Enclosure Heat Transfer System

With reference to FIG. 2, heat transfer band assembly 200 is comprisedof heat generating PCB assemblies 203 and 301, each of which are coupledto heat transfer band 104 in the same manner. The following explanationof the coupling method applies to both PCB assemblies, but refers onlyto PCB assembly 203 because FIG. 2 is a plan view; therefore, PCBassembly 301 which is underneath PCB assembly 203 cannot be shown.

PCB assembly 203 is coupled to heat transfer band 104 by meanscompression blocks 201 with a heat conductive gasket placed between theoverlapping portions of the PCB board and heat transfer band 104.Compression blocks 201 are secured to heat transfer band 104 by means ofcompression block fasteners and mating holes 201 a.

A section view of this fastening method into heat transfer band 104 isshown in the FIG. 3 b, illustrating a typical assembly of compressionblock fasteners 201 a, compression blocks 201 and thermal gaskets 201 c,respectively.

The source of the heat inside of the main enclosure cavity issubstantially generated by the electronic components 203 c and 203 d(FIG. 12) mounted on PCB assembly 203, and likewise similarly to PCBassembly 301 (not shown). In the exemplary embodiment of the presentdisclosure, these components consume approximately 13 watts ofelectrical power. Additionally in the exemplary embodiment, the internalbacklight and other components of LCD 305 consume approximately 4 watts.The heat generating components conduct their heat in the paths of leastthermal impedance that are provided by the present invention.

For PCB assemblies 203 and 301 (and similarly for references 604, 605,606, 607, 711, 712, 713, 714 of the alternate embodiments) mounted toheat transfer band 104, the component generated heat is coupled to heattransfer band 104 by the two methods described below.

PCB components to PCB (printed circuit board)—With reference to FIGS. 8and 8 a of an exemplary PCB construction, the PCB has at least oneinternal planer layer 807 of copper or other conductive material forelectrical purposes, but also for the conduction of heat in lateraldirections toward heat transfer band 104 coupling locations as shown inFIG. 2. Conductive vias 802, 804 and 804 a and their associated regions803, 806 and 805 a through 805 d, respectively, are provided for bothelectrical and thermal conduction from the PCB's outer surfaces to theinternal PCB conductive plane.

As depicted in the exemplary PCB construction of FIGS. 8 and 8 a, thereare at least three basic types of conductive vias and regions, each ofwhich are thermally and electrically connected. The descriptions belowapply to either side of the PCB assembly.

Conductive vias 804 a are located under substantial heat generatingcomponents 805 a, 805 b, 805 c and 805 d, and are connected to terminalsof said components (typically the ground terminals). First, heat istransferred through vias 804 a to conductive internal layer 807.Conductive vias 804 are located within interior heat conduction regions806 which are positioned as close as possible to said heat generatingcomponents. Second, heat is transferred from said regions through saidvias to conductive internal layer 807. Conductive vias 802 are locatedwithin perimeter heat conduction regions 803 which are positioned alongthe perimeter of the PCB. Third, heat is transferred to said regionsfrom said vias emanating from conductive internal layer 807 which servesas a path of thermal conduction for the heat generated by saidcomponents mounted to the exterior surfaces of the PCB, as describedabove.

With reference to FIG. 3 a, the heat from perimeter heat conductionregions 803 (FIGS. 8 and 8 a) of PCB assemblies 203 and 301 is conductedto heat transfer band 104 by means of abutment relationships. The PCBperimeter heat conduction regions 803 abut thermally conductive gasket(e.g., 201 c) in contact with heat transfer band 104.

It is important to note that there are practical limitations toachieving the aforementioned integral PCB heat transfer method due tosignal routing, placement density, and other PCB layoutconstraints—especially for portable products that require a high degreeof density for miniaturization. It should also be noted that theinsulating PCB material (typically and in this case some form offiberglass, though other materials e.g., silicon may be suitable)provides heat conduction as well. Accordingly, it should be noted thatthe method of using heat transfer through internal layer 807 need not beapplied to achieve the benefit of the heat transfer method of thepresent disclosure.

PCB Assembly to Internal Enclosure Air—A portion of the heat from theheat generating components mounted on PCB assemblies 203 and 201, andthe resulting heat transferred to the PCB structure, is transferred tothe air inside the enclosure 100, which transfers its heat to the heattransfer band 104, and ultimately to the external surrounding airthrough convection. It should be noted that fan 205 can be turned on tomake the temperature distribution within the enclosure more uniform,thereby ensuring that a maximum amount of surface area of heat transferband 104 is exposed to the heat content of the air inside enclosure. Ascan be seen in FIGS. 2 and 3, fan 205 is positioned in such a way as toblow air across the top and bottom surfaces of PCB assemblies 203 and301. IN some embodiments plural fans may be provided without departingfrom the scope of the present disclosure.

LCD to Heat Transfer Band—A similar method to transfer heat to theinternal air of the enclosure, as described above, applies to the heatgenerated by LCD 305, so it won't be repeated here.

With reference to FIG. 3 a, LCD 305 is attached to LCD mounting plate403 by means of fasteners located on flanges 403 b of FIG. 4. Thematerial of LCD mounting plate 403 is typically anodized aluminum, butmay be made out of other thermally conductive materials as well.Thermally conductive gasket 305 a is applied between the abuttingsurfaces of the rear of LCD 305 and the top side of LCD mounting plate403. Because the thermally conductive gasket material is generallyexpensive, its surface area is sized only to meet the heat transferrequirements of this portion of the enclosure assembly.

The heat transferred from LCD 305 is coupled to heat transfer band 104by securely fastening LCD mounting plate 403 to compression blocks 201,described earlier, by means of fasteners 201 a of FIG. 3 a inserted toholes 403 a of FIG. 4. As can be seen in FIG. 2, the top of compressionblocks 201 provide fastener holes 201 b for mounting LCD mounting plate403. A thermally conductive gasket (not shown) is installed between theoverlapping surfaces of LCD mounting plate 403 and compression blocks201.

It should be noted that the preferred embodiment of the presentdisclosure, LCD mounting plate 403 is mounted on the opposite side ofheat transfer band assembly 200 shown in FIG. 2. The explanation abovestill holds true.

The abutment relationships starting with the heat source and formingsaid heat transfer coupling path are: from LCD 305 through thermallyconductive gasket 305 a to LCD mounting plate 403; from LCD mountingplate 403 through a thermally conductive gasket (not shown) tocompression blocks 201; from compression blocks 201 through a furtherthermally conductive gasket (not shown) to PCB assembly 301; and fromPCB assembly 301 through thermally conductive gasket 201 c to heattransfer band 104.

It should be noted that LCD mounting plate 403 may also be mounteddirectly to heat transfer belt 104 with or without a thermallyconductive gasket, or grease (e.g. 201 c), the benefit of which would beimproved thermal coupling due to the absence of the PCB in the heatconduction path. Furthermore, it is contemplated that the function ofcompression blocks 201 may instead be achieved by incorporating saidfunction into LCD mounting plate 403, or some other fabricated part, inorder to achieve the same said benefit and the additional benefits ofminimization of parts and the simplification of the assembly.

Enclosure Ruggedness

With reference to FIG. 9, the ruggedness of enclosure 900 is enhanced bybumper system 102 a through 102 f in conjunction with strong enclosurewall materials consisting of metal heat transfer band 104 sandwichedbetween enclosure front 307 and the enclosure rear 308.

The material used for the bumpers is a synthetic rubber; however, anymaterial that sufficiently absorbs shock without being damaged and meetsthe other environmental conditions (such as operating temperature range,chemical resistance, ultraviolet resistance, etc.) may be used. Itshould be noted that the bumper will compress and deform to some degreeduring the impact event; therefore, the dimensions of the bumpers musttake this into account to prevent the protected enclosure surfaces fromtouching an planar impact surface.

More specifically, exemplary FIGS. 10 and 11 depict the front, rightside and rear views of the shock protection system. The methodsdescribed above for FIGS. 10 and 11 below apply to all sides of theenclosure, including the sides that are not shown, even though thegeometry and features may differ to some degree.

Although the present invention has been described in relation toparticular embodiments thereof, many other variations and modificationsand other uses will become apparent to those skilled in the art. It ispreferred, therefore, that the present invention be limited not by thespecific disclosure herein, but only by the appended claims.

1. An enclosed electronic apparatus comprising: an enclosure having anexterior surface; a first continuous heat-transfer band forming at leasta portion of the exterior surface of the enclosure, the first continuousheat-transfer band having first and second substantially continuouslateral edges on either side thereof, and one or more mounting points onan internal side of the continuous heat transfer band to which a printedcircuit board assembly is mountable; at least one printed circuit boardassembly mounted to the heat transfer band at the one or more mountingpoints, the printed circuit board assembly including at least onethermally conductive portion forming a thermal path between aheat-producing electronic component of the printed circuit boardassembly and the heat transfer band; a first enclosure portion sealing afirst continuous lateral edge of the heat transfer band againstpenetration of fluid or debris; and a second enclosure portion sealing asecond continuous lateral edge of the heat transfer band againstpenetration of fluid or debris, further comprising an encoder shaftopening in one of the first enclosure portion and a second enclosureportion; an encoder mounted with the electronic apparatus, and encodershaft thereof extending through the encoder shaft opening; a continuousshaft gasket in compression between the encoder shaft and the encodershaft opening; and an encoder knob mounted to the encoder shaft, theencoder knob covering the area of encoder shaft opening.
 2. The enclosedelectronic apparatus according to claim 1, further comprising a sealinggrease applied to the interface between the encoder shaft opening andthe continuous shaft gasket, and to the interface between the continuousshaft gasket and the encoder shaft.
 3. The enclosed electronic apparatusaccording to claim 1, wherein the encoder knob presents at least one ofa small clearance between itself and the surface of the respective firstenclosure portion and second enclosure portion; and a small clearancebetween itself and a wall of the encoder shaft opening.
 4. An enclosedelectronic apparatus comprising a sealed enclosure; an encoder shaftopening in the sealed enclosure; an encoder mounted with the sealedenclosure, an encoder shaft thereof extending through the encoder shaftopening; a continuous shaft gasket in compression between the encodershaft and the encoder shaft opening; and an encoder knob mounted to theencoder shaft, the encoder knob covering the area of encoder shaftopening.
 5. The enclosed electronic apparatus according to claim 4,further comprising a sealing grease applied to the interface between theencoder shaft opening and the continuous shaft gasket, and to theinterface between the continuous shaft gasket and the encoder shaft. 6.The enclosed electronic apparatus according to claim 4, wherein theencoder knob presents at least one of a small clearance between itselfand the surface of the respective first enclosure portion and secondenclosure portion; and a small clearance between itself and a wall ofthe encoder shaft opening.